U.S. patent application number 12/767550 was filed with the patent office on 2011-10-27 for clutch system and methods.
This patent application is currently assigned to KIT MASTERS INC.. Invention is credited to Craig Swanson.
Application Number | 20110259699 12/767550 |
Document ID | / |
Family ID | 44814845 |
Filed Date | 2011-10-27 |
United States Patent
Application |
20110259699 |
Kind Code |
A1 |
Swanson; Craig |
October 27, 2011 |
Clutch System and Methods
Abstract
Some embodiments of a clutch system or method include a fan
clutch device having a clutch shut-off system permits a cooling fan
to continue to provide airflow even when the friction ring is worn
down to a level that requires replacement.
Inventors: |
Swanson; Craig; (Perham,
MN) |
Assignee: |
KIT MASTERS INC.
Perham
MN
|
Family ID: |
44814845 |
Appl. No.: |
12/767550 |
Filed: |
April 26, 2010 |
Current U.S.
Class: |
192/66.2 ;
192/66.1 |
Current CPC
Class: |
F16D 25/0632
20130101 |
Class at
Publication: |
192/66.2 ;
192/66.1 |
International
Class: |
F16D 13/24 20060101
F16D013/24; F16D 13/22 20060101 F16D013/22 |
Claims
1. A fan clutch device to be removably mounted to a drive pulley,
the fan clutch device comprising: an input portion that rotates
with a drive pulley when the fan clutch device is mounted to the
drive pulley; an output portion for receiving a fan blade device
and having a friction ring that reciprocates in an axial direction
relative to the input portion between an engaged position in which
the friction ring frictionally engages with an opposing surface of
the input portion to drive the output portion to rotate with the
input portion and a disengaged position in which the friction ring
is spaced apart from the opposing surface of the input portion; and
a self-activating, clutch shut-off system that causes continuous
friction engagement between the friction ring and the opposing
surface of the input portion in response to the friction ring
wearing down below a threshold thickness.
2. The device of claim 1, wherein the self-activating, clutch
shut-off system prevents movement of the friction ring from the
engaged position to the disengaged position in response to the
friction ring wearing down below the threshold thickness.
3. The device of claim 2, wherein the self-activating, clutch
shut-off system is housed in the output portion and comprises at
least two elements.
4. The device of claim 3, wherein the clutch shut-off system is
self-activating in that the two elements engage one another only
when the friction ring is worn down below the threshold thickness,
wherein the friction ring is prevented from moving from the engaged
position to the disengaged position when the two elements engage
one another.
5. The device of claim 4, wherein the two components of the
self-activating, clutch shut-off system comprise a seal member and
an interior surface of a fluid-receiving space, wherein the seal
member engages the interior surface of the fluid-receiving space to
form a fluid seal only when the friction ring is worn down below
the threshold thickness.
6. The device of claim 5, wherein when the seal member sealingly
engages the interior surface of the fluid-receiving space, a
surface area of the fluid-receiving space that is exposed to
pressurized fluid is substantially reduced, thereby preventing the
pressurized fluid in the fluid-receiving space from causing the
friction ring to move from the engaged position to the disengaged
position.
7. The device of claim 1, wherein the self-activating, clutch
shut-off system prevents movement of the friction ring to the
disengaged position in response to the friction ring wearing down
below the threshold thickness and without external controls.
8. The device of claim 1, wherein the output portion comprises: a
hub portion that, when the fan clutch device is mounted to the
drive pulley, is selectively movable relative to the drive pulley;
and a piston portion adjustable in the axial direction relative to
the drive pulley when the fan clutch device is mounted to the drive
pulley, the piston portion being axially adjustable so as to shift
the friction ring between the engaged position and the disengaged
position; a fluid-receiving space being at least partially defined
by a surface of the piston portion, the fluid-receiving space being
configured to receive pressurized fluid to urge the friction ring
to the disengaged position; and at least one spring device to that
biases the friction ring to the engaged position.
9. The device of claim 8, wherein the clutch ring is a
frusto-conical clutch ring that is arranged radially outward of the
output portion.
10. A fan clutch system, comprising: a drive pulley that rotates
about a rotational axis; a clutch device removably mounted to the
drive pulley, the clutch device comprising: an input portion that
rotates with a drive pulley; an output portion having a friction
ring that reciprocates in an axial direction relative to the input
portion between an engaged position in which the friction ring
frictionally engages with an opposing surface of the input portion
to drive the output portion to rotate with the input portion and a
disengaged position in which the friction ring is spaced apart from
the opposing surface of the input portion; and an internal
mechanical shut-off system that is housed in the output portion and
that is automatically activated, in response to the friction ring
wearing down below a selected level, to prevent movement of the
friction ring from the engaged position to the disengaged position;
a fan blade device mounted to the output portion of the clutch
device so as to rotate when the friction ring is in the engaged
position.
11. The system of claim 10, wherein the internal mechanical
shut-off system causes continuous friction engagement between the
friction ring and the opposing surface of the input portion in
response to the friction ring wearing down below the selected
level.
12. The system of claim 11, wherein the internal mechanical
shut-off system comprises at least two elements, and the internal
mechanical shut-off system is self-activating in that the two
elements engage one another only when the friction ring is worn
down below the selected level, wherein the friction ring is
prevented from moving from the engaged position to the disengaged
position when the two elements engage one another.
13. The system of claim 12, wherein the two components of the
internal mechanical shut-off system comprise a seal member and a
surface of a fluid-receiving space, wherein the seal member engages
the surface of the fluid-receiving space to form a fluid seal only
when the friction ring is worn down below the selected level, and
wherein when the seal member sealingly engages the surface of the
fluid-receiving space, a surface area of the fluid-receiving space
that is exposed to pressurized fluid is substantially reduced such
that the pressurized fluid in the fluid-receiving space is hindered
from causing the friction ring to move from the engaged position to
the disengaged position.
14. The system of claim 10, wherein the output portion of the
clutch device comprises: a hub portion that is selectively movable
relative to the drive pulley; and a piston portion adjustable in
the axial direction relative to the drive pulley so as to shift the
friction ring between the engaged position and the disengaged
position; a fluid-receiving space being at least partially defined
by a surface of the piston portion, the fluid-receiving space being
configured to receive pressurized fluid to urge the friction ring
to the disengaged position; and at least one spring device to that
biases the friction ring to the engaged position.
15. The system of claim 14, wherein the clutch ring is a
frusto-conical clutch ring that is arranged radially outward of the
output portion.
16. A method of operating a fan clutch device that is removably
mounted to a drive pulley, the method comprising: rotating an input
portion of a fan clutch device with a drive pulley; reciprocating a
friction ring of an output portion of the fan clutch device in an
axial direction between an engaged position and a disengaged
position, wherein when the friction ring is in the engaged
position, the friction ring frictionally engages with an opposing
surface of the input portion to drive the output portion to rotate
with the input portion, and wherein when the friction ring is in
the disengaged position, the friction ring is spaced apart from the
opposing surface of the input portion; and in response to the
friction ring wearing down below a threshold thickness,
automatically shutting off the fan clutch device without user
intervention while the friction ring is in the engaged position
such that friction ring is hindered from moving to the disengaged
position.
17. The method of claim 16, wherein the step of automatically
shutting off the fan clutch device comprises causing an internal
mechanical shut-off system to self-activate in response to the
friction ring wearing down below the threshold thickness, wherein
the internal mechanical shut-off system is housed within the output
portion of the fan clutch device and causes continuous friction
engagement between the friction ring and the opposing surface of
the input portion in response to the friction ring wearing down
below the threshold thickness.
18. The method of claim 17, wherein the step of automatically
shutting off the fan clutch device comprises causing at least two
elements of the internal mechanical shut-off system to engage one
another only when the friction ring is worn down below the
threshold thickness, wherein the friction ring is prevented from
moving from the engaged position to the disengaged position when
the two elements engage one another.
19. The method of claim 18, wherein the two components of the
internal mechanical shut-off system comprise a seal member and a
surface of a fluid-receiving space, wherein the seal member engages
the surface of the fluid-receiving space to form a fluid seal only
when the friction ring is worn down below the threshold
thickness.
20. The method of claim 19, wherein when the seal member sealingly
engages the surface of the fluid-receiving space, a surface area of
the fluid-receiving space that is exposed to pressurized fluid is
substantially reduced such that the pressurized fluid in the
fluid-receiving space is hindered from causing the friction ring to
move from the engaged position to the disengaged position.
Description
TECHNICAL FIELD
[0001] This document relates to a rotational control apparatus,
such as a clutch apparatus to control the rotation of a fan device
in a vehicle.
BACKGROUND
[0002] Vehicle transmission systems, cooling systems, and braking
systems may employ clutches or like devices to selectively transmit
rotational forces from a drive source to an output member. For
example, some cooling systems employ fan clutches that control the
output rotation of engine cooling fans. Such a fan clutch can be
driven by a drive pulley that rotates in response to the vehicle
engine.
[0003] In general, the clutch can be operated to engage (or
disengage) opposing clutch surfaces, which rotationally
interconnect (or rotationally disconnect) the drive pulley and the
output member. In an example related to fan clutches, when the
clutch is shifted to the engaged position, friction surfaces engage
and the output member (carrying fan blades) is driven to rotate
along with the drive pulley. Over time, the friction surface can
become worn, requiring replacement.
[0004] In some cases, the fan clutch in a vehicle can become
inoperable due to wearing of the friction surfaces. For example, in
some conventional fan clutch devices, a friction clutch ring is
unable to engage an opposing friction surface when the friction
clutch ring is worn below a threshold thickness. Accordingly, the
fan clutch device is unable to force engagement of the friction
surfaces and the fan blades are not driven to rotate (e.g., no
cooling airflow is provided). Due to the lack of cooling airflow,
the vehicle's engine may overheat or otherwise become highly
inefficient.
[0005] These conventional fan clutch devices are typically supplied
with a set of "come home" bolts for separate storage by the vehicle
operator (e.g., placement in the vehicle cabin for use at a much
later time. Thus, after a period of years when the friction ring of
the fan clutch device is worn down below a threshold level so that
the friction surfaces are no longer able to engage, the vehicle
operator must attempt to locate the "come home" bolts that were
stored years earlier. If the "come home" bolts are located, the
vehicle operator must then attempt to install the bolts to the fan
clutch device in the engine compartment. In general, the "come
home" bolts are installed onto the outer periphery of the clutch
device so as to temporarily bolt the output member to the input
member, thereby causing permanent rotation of the fan blades until
the vehicle can be driven to a repair facility. For vehicles such
as large semi trucks or buses, the installation of the "come home"
bolts may occur on the side of the road if the fan clutch fails
during a long journey.
SUMMARY
[0006] Some embodiments of a clutch system or method include a fan
clutch device having a clutch shut-off system permits a cooling fan
to continue to provide airflow even when the friction ring is worn
down to a level that requires replacement. Moreover, the clutch
shut-off system can automatically operate (e.g., without any user
intervention or external controls) to prevent disengagement at the
friction surfaces between the input portion and the output portion
of the clutch device. For example, the fan clutch device can be
equipped with an internal mechanical shut-off system that is
self-activated, in response to the friction ring wearing down below
a selected level, to prevent movement of the friction ring from the
engaged position to the disengaged position.
[0007] Particular embodiments described herein include a fan clutch
device to be removably mounted to a drive pulley. The fan clutch
device may include an input portion that rotates with a drive
pulley when the fan clutch device is mounted to the drive pulley.
The device may also include an output portion for receiving a fan
blade device and having a friction ring that reciprocates in an
axial direction relative to the input portion between an engaged
position and a disengaged position. When in the engaged position,
the friction ring may frictionally engage with an opposing surface
of the input portion to drive the output portion to rotate with the
input portion. When in the disengaged position, the friction ring
may be spaced apart from the opposing surface of the input portion.
The device may further comprise a self-activating, clutch shut-off
system that causes continuous friction engagement between the
friction ring and the opposing surface of the input portion in
response to the friction ring wearing down below a threshold
thickness.
[0008] In some embodiments, a fan clutch system may include a drive
pulley that rotates about a rotational axis, and a clutch device
removably mounted to the drive pulley. The clutch device may
include an input portion that rotates with a drive pulley. Also,
the clutch device may include an output portion having a friction
ring that reciprocates in an axial direction relative to the input
portion between an engaged position in which the friction ring
frictionally engages with an opposing surface of the input portion
to drive the output portion to rotate with the input portion and a
disengaged position in which the friction ring is spaced apart from
the opposing surface of the input portion. The clutch device may
further include an internal mechanical shut-off system that is
housed in the output portion. The internal mechanical shut-off
system may be automatically activated, in response to the friction
ring wearing down below a selected level, to prevent movement of
the friction ring from the engaged position to the disengaged
position. The system may also include a fan blade device mounted to
the output portion of the clutch device so as to rotate when the
friction ring is in the engaged position.
[0009] A number of embodiments described herein include a method of
operating a fan clutch device that is removably mounted to a drive
pulley. The method may include rotating an input portion of a fan
clutch device with a drive pulley. The method may also include
reciprocating a friction ring of an output portion of the fan
clutch device in an axial direction between an engaged position and
a disengaged position. When the friction ring is in the engaged
position, the friction ring frictionally may engage with an
opposing surface of the input portion to drive the output portion
to rotate with the input portion. When the friction ring is in the
disengaged position, the friction ring may be spaced apart from the
opposing surface of the input portion. The method may further
include, in response to the friction ring wearing down below a
threshold thickness, automatically shutting off the fan clutch
device without user intervention while the friction ring is in the
engaged position such that friction ring is hindered from moving to
the disengaged position.
[0010] In one aspect, the step of automatically shutting off the
fan clutch device may include causing an internal mechanical
shut-off system to self-activate in response to the friction ring
wearing down below the threshold thickness. The internal mechanical
shut-off system may be housed within the output portion of the fan
clutch device and may cause continuous friction engagement between
the friction ring and the opposing surface of the input portion in
response to the friction ring wearing down below the threshold
thickness.
[0011] Some or all of the embodiments described herein may provide
one or more of the following benefits. First, some embodiments of a
clutch device can include clutch shut-off system that causes a
cooling fan to provide continuous airflow even when a friction ring
of the clutch device is worn down below a threshold thickness level
and requires replacement. As such, the output portion of the clutch
device (and the fan blade device attached thereto) will
continuously rotate with the input portion of the clutch device
even after the friction ring is worn down and needs replacement,
thereby providing cooling airflow to the vehicle engine without the
need for "come home" bolts or other user intervention on the clutch
device. Because the clutch shut-off system causes the clutch device
to default to a permanent engaged position when the friction ring
incurs a predetermined amount of wear, the vehicle engine will not
be subjected to a loss of cooling airflow during a journey and the
vehicle operator will not be forced to intervene or service the
clutch device (e.g., on the side of the road) before driving to a
service station.
[0012] Second, some embodiments of the clutch shut-off system can
operate as a self-activated mechanical system that, without any
user intervention or external controls, forces the friction ring to
remain in a frictionally engaged condition. In addition, the clutch
shut-off system can be housed within the clutch device, such as
within the output portion of the clutch device, without increasing
the radial size of the clutch device.
[0013] Third, some embodiments of the clutch device can provide
substantial torque transfer capabilities in a relatively compact
assembly. For example, some embodiments of the clutch device may
provide torque ratings in the range of approximately 3000 in-lbs to
approximately 6000 in-lbs.
[0014] The details of one or more embodiments of the invention are
set forth in the accompanying drawings and the description below.
Other features, objects, and advantages of the invention will be
apparent from the description and drawings, and from the
claims.
DESCRIPTION OF DRAWINGS
[0015] FIG. 1 is a perspective exploded view of a system including
a fan clutch device, in accordance with some embodiments.
[0016] FIG. 2A is a cross-sectional view of the system of FIG. 1,
including the fan clutch device.
[0017] FIGS. 2B-2C are cross-sectional views of portions of the fan
clutch device of FIG. 2A.
[0018] FIG. 3 is a cross-sectional view of the system of FIG. 2A,
with an output portion shifted to a disengaged position.
[0019] FIG. 4A is a cross-sectional view of the system of FIG. 1,
including the fan clutch device having worn friction material, in
accordance with some embodiments.
[0020] FIGS. 4B-4C are cross-sectional views of portions of the fan
clutch device of FIG. 4A.
[0021] FIG. 5 is a cross-sectional view of the system of FIG. 4A
with the output portion locked in an engaged position.
[0022] Like reference symbols in the various drawings indicate like
elements.
DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS
[0023] Referring to FIGS. 1, 2A-2C, some embodiments of a clutch
system 10 include a clutch device 100 that provides rotational
output for a cooling fan device 20 having a number of fan blades.
The clutch device 100 includes an input portion 110 and an output
portion 130 adjustable between an engaged position (FIG. 2) and a
disengaged position (FIG. 3). In this embodiment, the clutch device
100 can include opposing clutch surfaces 114 and 134 configured
such that, when the clutch device 100 is in an engaged position,
the rotational motion of the input portion 110 (as driven by a
drive member 30 shown in FIG. 1) can be transmitted via the
frictional interface between the opposing clutch surfaces 114 and
134 so that the output portion 130 and the fan blade device 20
mounted thereto are driven at a first speed.
[0024] After extended use of the clutch device 100 (e.g., while the
clutch device 100 is transitioned between the engaged and
disengaged positions, and the like), the friction material can be
worn from one or both of the clutch surfaces 114 and 134. For
example, the friction material of a friction ring 132 that defines
the clutch surface 134 may reduce in thickness after an extended
period of use due to the repeated frictional engagements between
the opposing surfaces 114 and 134. In this embodiment, the clutch
surface 114 is a frusto-conical clutch surface that extends along
an inner surface of an input ring 112 and the corresponding clutch
surface 134 is a frusto-conical clutch surface located on the outer
surface of a replaceable friction ring 132. The input ring 112 and
the friction ring 132 may comprise a metallic, ceramic, or other
material that is capable of providing frictional engagement and is
capable of dissipating heat generated at the frictional interface.
In some embodiments, the replaceable friction ring 132 comprises a
friction material such that as the clutch device 100 is used, the
friction ring 132 can wear at a greater rate than the input ring
112.
[0025] As described in more detail below, the clutch device 100 can
include clutch shut-off system 150 that permits the fan blade
device 20 to continue to provide airflow even when the friction
ring 132 is worn down below a threshold level that requires
replacement. In these embodiments, the clutch shut-off system 150
can be self-activated, without any user intervention or external
controls, to prevent disengagement at the friction surfaces 114 and
134 between the input portion 110 and the output portion 130 of the
clutch device 100. For example, as described in more detail below
in connection with FIGS. 4A-4C, the clutch shut-off system may
operate as an internal mechanical shut-off system that is
automatically activated, in response to the friction ring 132
wearing down below a selected level, to prevent movement of the
friction ring 132 from the engaged position to the disengaged
position. As such, the output portion 130 (and the fan blade device
20 attached thereto) will continuously rotate with the input
portion 110 of the clutch device 100 even after the friction ring
132 is reduced to a thickness that requires ring replacement,
thereby providing cooling airflow to the vehicle engine without the
need for "come home" bolts or other user intervention on the clutch
device 100.
[0026] Thus, when the shut-off system 150 is activated (described
in more detail below), the fan blade device 20 would continuously
rotate with the drive pulley 30, thereby providing cooling airflow
at all times and indicating to a vehicle operator that the clutch
device 100 may require inspection and subsequent replacement of the
friction ring 132. Since the clutch device 100 defaults to a
permanent engaged position when the friction ring 132 incurs a
predetermined amount of wear, the vehicle engine will not be
subjected to a loss of cooling airflow during a journey and the
vehicle operator will not be forced to intervene or service the
clutch device 100 (e.g., on the side of the road) before driving to
a service station. Furthermore, regular visual inspection of the
friction surfaces 114 and 134 may be reduced or unnecessary, thus
saving the vehicle operator money and reducing the amount of
down-time of the vehicle.
[0027] Briefly, in operation, the clutch system 10 may include a
drive member 30 (e.g., a drive pulley as shown in FIG. 1, a drive
shaft, or the like) that is rotated at a first speed due to
connection with an engine output shaft via a belt, chain, gear, or
the like. In some embodiments, the clutch system 10 includes the
input portion 110 that can be directly or indirectly mounted to the
drive pulley 30 so as to rotate at the first speed with the drive
pulley 30. In the depicted embodiments, the input portion 110
includes the input ring 112 that is directly mounted to the drive
pulley 30 via mounting bolts 32. The clutch system 10 also includes
the output portion 130 having at least one component that can be
actuated to engage or disengage with the input portion 110. For
example, the output portion 130 can include a piston 140 that
reciprocates axially relative to a hub 160 (which remains axially
stationary relative to the input portion 110) so as to shift the
friction ring 132 into engagement (FIG. 2A) or disengagement (FIG.
3, refer to a disengagement gap 102) with the opposing clutch ring
112 of the input portion 110. When the output portion 130 is
adjusted to shift the friction ring 132 to the engaged position
(FIG. 2A), the output portion 130 is urged to rotate at the first
speed with the input portion 110 and the drive pulley 30. Note that
the distance of the shift and the length of the disengagement gap
102 are exaggerated in the figures for purposes of
illustration.
[0028] Still referring to FIGS. 1, 2A-2C, in some embodiments, the
clutch device 100 can include features (e.g., a coil spring 170, a
plurality of springs, or another biasing device) to bias the
friction ring 132 to the engaged position and features (e.g., a
fluid-receiving chamber 180 that can be filled with a pressurized
fluid) to urge the friction ring 132 to the disengaged position.
For example, when the clutch device 100 is engaged, the spring 170
can urge the piston 140 to move in an axially rearward direction
toward the pulley 30, thereby causing the friction ring 132 to
frictionally engage the opposing ring 112 at the interface of
surfaces 114 and 134. Such frictional engagement of the clutch ring
112 causes the fan blade device 20 (connected to the output portion
130) to rotate at substantially the speed of the drive pulley
30.
[0029] In some embodiments, rotation of the fan blade device 20 can
generate a flow of cooling air directed in an axial direction. For
example, when the clutch device 100 drives the output portion 130
and the fan blade device 20 to rotate, the fan blades can create a
cooling airflow directed generally axially toward the drive pulley
30 (FIG. 2A) and a vehicle engine radiator or cooling system.
[0030] Referring now to FIGS. 1 and 2A, in some embodiments the
drive pulley 30 is rotatably coupled to a support shaft 40 by one
or more bearings 37. A nut or collar device 42 is secured to the
support shaft 40 and is abutted to the bearing 37 so that the
bearings 37 remain substantially fixed in the axial direction
relative to the support shaft 40. The drive pulley 30 receives a
belt, chain, gear or the like in order to force the drive pulley 30
to rotate in a particular direction about an axis 35. In this
embodiment, the support shaft 40 is substantially stationary, and
the drive pulley 30 includes a belt engagement surface 34.
Rotational power from a vehicle motor or the like may be
transmitted through a belt (not shown) to the belt engagement
surface 34, thereby urging the drive pulley 30 to rotate about the
central axis 35 of the support shaft 40.
[0031] A fluid supply input channel 50 extends into the support
shaft 40 for connection to a fluid supply reservoir (not shown). A
supply channel 52 extends from the fluid supply input 50, a portion
of which extends in a substantially axial direction along the
central axis 35. In this embodiment, the supply channel 52 extends
through a cylindrical outlet 45, which has a mating end 47 to mate
with a face seal 157 of the clutch device 100. As such, when the
clutch device 100 is mounted to the drive pulley 30, the face seal
157 is pressed against the mating end 47 to form a mechanical seal.
A fluid channel 182 extending axially through the face seal 157 is
substantially axially aligned with the central axis 35.
Accordingly, the pressurized fluid may be transmitted from the
fluid supply input 50, through the supply channel 52 and the fluid
channel 182, and into the fluid-receiving chamber 180 of the clutch
system 10. In some embodiments, the mating end 47, the face seal
157, or both may comprise metals, polymers, or composite materials
that can substantially maintain the mechanical seal therebetween
while the clutch system 10 is selectively rotated relative to the
support shaft 40. The fluid transmitted to the fluid-receiving
chamber 180 of the clutch system 10 may be any suitable liquid or
gas, as described in more detail below. Such fluids may be
received, for example, from a pneumatic air supply system or a
hydraulic oil supply system.
[0032] In some embodiments, the output portion 130 of the clutch
system 10 includes the piston 140 and the hub 160. The piston 140
includes a mounting plate 142, a first spline member 144, and a
spring-engaging member 146, that are assembled together. Likewise,
the hub 160 includes a spring-engaging plate 162 and a second
spline member 164 that are assembled together. The piston 140 is
movable in an axial direction relative to the hub 160 and is
substantially stationary in a rotation direction relative to the
hub 160. As such, the piston 140 can move axially relative to the
hub 160, but rotates at generally the same speed as the hub 160. In
this embodiment, the motion of the piston 140 relative to the hub
160 is accomplished by way of a spline connection between the first
spline member 144 and the second spline member 164. In other
embodiments, the motion of the piston 140 relative to the hub 160
may be accomplished using one or more bushings that permit relative
axial movement and anti-rotation dowels that substantially prevent
relative rotation between the piston 140 and the hub 160.
[0033] In some embodiments, the mounting plate 142 of the piston
140 is configured to receive an output instrument (e.g., a fan
blade device 20 depicted in FIG. 1 or another instrument to be
selectively rotated). In particular, the mounting plate 142 may
include studs 23 that are configured to receive the output
instrument. As shown in FIG. 1, the fan blade device 20 can be
configured to fit over the output portion 130. The fan blade device
20 can include a plurality of fan blade structures 22 that are
arranged to generate air flow (e.g., as part of a vehicle's engine
cooling system). The fan blade structures 22 can be angled,
tapered, curved, or otherwise configured to direct the output of
air flow. In this embodiment, the fan blade device 20 includes
mounting holes 24 that are configured to receive the studs 23
extending from the clutch system 10. In alternative embodiments,
the output portion 130 of the clutch system 10 may be configured to
receive an output instrument other than a fan blade device 20. For
example, the mounting plate 142 may be configured to connect with
other components that are to be selectively rotated, such as output
shafts, gears, brake systems, and the like.
[0034] Referring now to FIGS. 2A-2C, as previously described, the
mounting plate 142 can be assembled together with the first spline
member 144 and the spring-engaging member 146 to form the piston
140. The mounting plate 142 of the piston 140 partially defines the
fluid-receiving chamber 180 and has surfaces 151, 152 that are
acted upon by the pressurized fluid in the fluid-receiving chamber
180 so as to overcome the spring bias of the spring device 170. The
mounting plate 142 is fixedly coupled to the spring-engaging member
146, for example, by bolts 145 fastened into threaded cavities and
slidably coupled to the spring engaging member 146. The first
spline member 144 is fixedly coupled to the mounting plate 142, for
example, by threads on an external surface of the first spline
member 144 that are mated into a threaded cavity of the mounting
plate 142. Accordingly, the piston components 142, 144, and 146 can
collectively move relative to the hub 160 (e.g., shift axial
positions relative to the hub 160 in this embodiment).
[0035] Referring again to FIGS. 1 and 2A, the hub 160 includes the
second spline member 164 assembled together with the
spring-engaging plate 162. The second spline member 164 can be
fixedly coupled to the spring-engaging plate 162, for example, by
threads on an external surface of the second spline member 164 that
are mated into a threaded cavity of the spring-engaging plate 162.
The second spline member 164 at least partially defines the fluid
channel 182 extending from the face seal 157 to the chamber 180. At
least one bearing 114 is disposed between the hub 160 (e.g., the
second spline member 164) and the input ring 112. As previously
described, the input ring 112 is secured to the drive pulley 30 and
rotates along with the drive pulley 30. As such, the bearings 114
permit the hub 160 (including the second spline member 164 and the
spring-engaging plate 162) to rotate relative of the input ring 112
and the drive pulley 30. In this embodiment, the bearings 114 are
disposed along an outer circumferential surface 165 of the second
spline member 164. The bearing 114 may be secured to the second
spline member 164 and the input ring 112 using any number of
securing means, such as collar devices, locking nuts, locking
rings, tongue and groove arrangements, or the like. In this
embodiment, the bearings 114 are secured to the hub 160 using a
locking nut 116 so that the bearings 114 remain substantially
stationary relative to the hub 160 in the axial direction. The
bearings 114 are secured to the input ring 112 using a locking ring
such that the bearings 114 remain substantially stationary relative
to the input ring 112 in the axial direction. Therefore, in this
embodiment, the hub 160 may rotate independently of the input ring
112 and drive pulley 30, but the hub 160 remains substantially
stationary in the axial direction relative to the input ring 112
and drive pulley 30.
[0036] In some embodiments, the spring 170 is arranged between the
piston 140 and the hub 160 so as to bias the piston 140 toward one
of a first position and second position relative to the hub. In
these embodiments, the spring 170 is a single, coiled spring that
has an inner and outer diameter to fit securely between the
spring-engaging plate 146 of the piston 140 and the spring-engaging
plate 162 of the hub 160. The spring 170 may be arranged coaxial
with the central axis 35 of the clutch device 100. Using only a
single spring may simplify assembly and disassembly of the clutch
system 10 during manufacture or repair. Because only one spring 170
need be arranged between plates 146 and 162, less time is required
to properly align the spring 170 during assembly. Alternatively,
other embodiments may use a more complex arrangement having a
greater number of smaller springs that are positioned adjacent one
another between plates 142 and 162.
[0037] Referring now to FIGS. 2A-2C and 3, when the clutch device
100 is assembled, the spring 170 is compressed between a
spring-engaging surface 147 of the piston 140 and the spring
engaging surface 161 of the hub 160. Such an arrangement urges the
piston 140 in an axial direction toward the drive pulley 30. Thus,
in this embodiment, the spring force applied by the spring 170
biases the piston 140 such that the engagement surface 134 of the
friction ring 132 is urged against the opposing engagement surface
114 of the input ring 112, which is mounted to the drive pulley 30
using the bolts 32. Thus, as shown in FIG. 2, the friction ring 132
is biased by the spring device 170 to the engaged position. In
particular, the friction ring 132 is mounted to the mounting plate
142 so that the engagement surface 134 of the friction ring 132 is
adjacent to the engagement surface 114 of the input ring 112. When
the engagement surface 114 presses against the opposing surface
134, the output portion 130 frictionally engages the input portion
110, which is mounted to the drive pulley 30, and the output
portion 130 thereby rotates at the first speed with the drive
pulley 30.
[0038] In some embodiments, the input ring 112 may comprise a
metallic, ceramic, or other material that is capable of providing
frictional engagement and is capable of dissipating heat generated
at the frictional interface. For example, some embodiments of the
input ring 112 may comprise a material having a static coefficient
of friction in the range of approximately 0.2 to approximately 0.6
and, in particular embodiments may comprise a material having a
static coefficient of friction in the range of approximately 0.4 to
approximately 0.5. The input ring 112 can be arranged such that a
portion is radially outward of the output portion 130 such that the
input ring 112 can be secured to the pulley 30. In some
embodiments, the input ring 112 may include the frusto-conical
engagement surface 114, on the inner edge of the input ring 112,
which at least partially extends in a non-radial direction. In such
circumstances, the inner surface of the input ring 112 may have an
increasingly larger outer diameter as the engagement surface 114
extends away from the drive pulley 30. Furthermore, in this
embodiment, the engagement surface 114 and the outer conical
surface of the spring-engaging member 146 may be generally parallel
to one another so that the friction ring 132 has a generally
uniform wall thickness. Thus, the radii of both the spring-engaging
member 146 and the inner conical surface of the input ring 112 may
become increasingly larger as the input ring 112 extends away from
the drive pulley 30.
[0039] In some embodiments, the friction ring 132 is secured to the
spring-engaging member 146, which rotates with the output portion
130, and the friction ring 132 can be arranged radially inward of
the opposing engagement surface 114 of the input ring 112 that
rotates with the input portion 110. Thus, the friction ring 132 may
be positioned radially outward of the output portion 130 and
radially inward of the engagement surface 114. The shape and
orientation of the frusto-conical friction ring 132 and the
complementary engagement surface 114 may provide the clutch system
10 with a conical wedging action. For example, when the clutch
device 100 is in the engaged configuration (refer to FIG. 2A), the
input ring 112 and opposing friction ring 132 may abut each other
forming a frusto-conical frictional interface between the clutch
surfaces (e.g., the engagement surface 114 and the opposing surface
134). This conical wedging action may improve the engagement
friction, thereby providing an increase in the torque transfer
capabilities. For example, some embodiments of the clutch device
100 (in which the friction ring 132 has a maximum outer radius of
less than 12 inches, less than 10 inches, about 4 inches to about 8
inches, and preferably about 6.4 inches) may provide torque ratings
of approximately 2700 in-lbs, 2800 in-lbs, 2900 in-lbs, 3000
in-lbs, or more, and particular embodiments may provide torque
ratings in the range of approximately 3000 in-lbs to approximately
6000 in-lbs. The substantial torque transfer capabilities may be
caused by a number of factors, such as the coefficient of friction
of the input ring 112, the conical angle of the input ring 112, the
spring force applied by the spring 170, and other factors that
affect the torque rating of the clutch system 10.
[0040] Referring more closely to FIG. 3, the output portion 130 of
the clutch system 10 may disengage the input portion 110 when fluid
is introduced into the chamber 180 under sufficient pressure to
axially shift the piston 140 relative to the hub 160. When the
piston 140 shifts axially (e.g., an axial displacement distance
104), the engagement surface 134 is shifted away from the opposing
surface 114 (e.g., yielding the disengagement gap 102). In this
position, the output portion 130 (including the piston 140 and hub
160 in this embodiment) is no longer driven to rotate at the first
speed due to the direct friction engagement with the input portion
110. As previously described, fluid may enter the chamber 180
through the fluid channel 182, for example as represented by the
arrows 183. In this embodiment, the fluid-receiving chamber 180 is
at least partially defined by the space between the mounting plate
142 of the piston 140 and the spring-engaging plate 162 of the hub
160. Fluid pressure within the chamber 180 creates a force against
the piston 140 (e.g., at the surfaces 151, 152 of the mounting
plate 142 as represented by arrows 181) in opposition to the force
bias of the spring 170. When a sufficient amount of fluid pressure
has built up in the chamber 180, the force imparted by the fluid on
the piston 140 is enough to overcome the bias of the spring 170,
forcing the piston 140 in an axial direction away from the drive
pulley 30.
[0041] As shown in FIG. 3, when the friction ring 132 of the output
portion 130 is shifted away from the input ring 112 of the input
portion 110, the gap 102 is created between the engagement surface
114 of the input ring 112 and the friction surface 134 of the
opposing friction ring 132. It should be understood that the
displacement distance 104 of the piston 140 and the length of the
gap 102 depicted in FIG. 3 may be exaggerated in the drawings for
purposes of illustration. The gap 102 can be sufficient to
eliminate contact between the input ring 112 and the opposing
friction ring 132. In such circumstances, the output portion 130
(including the piston 140 and hub 160 in this embodiment) is no
longer driven to rotate by direct engagement with the input portion
110. When the piston 140 is shifted to the disengaged position
depicted in FIG. 3, the output portion 130 (including the piston
140 and hub 160 in this embodiment) can rotate relative to the
input portion 110 and drive pulley 30 due to the bearing connection
114. Accordingly, the output portion 130 may rotate at a second,
slower speed (e.g., a zero speed in some circumstances) even though
the drive pulley 30 continues to rotate at the first speed.
[0042] As previously described, the gap 102 between the engagement
surface 114 and the opposing friction surface 134 is created when a
fluid under sufficient pressure is received in the chamber 180. If
force from the fluid pressure in the chamber 180 is sufficient to
overcome the force of the bias of the spring 170, the piston 140 is
shifted in the axial direction away from the drive pulley 30. In
some embodiments, the fluid pressure in the chamber 180 that is
required to overcome the spring force may be approximately
predetermined from the spring constant, the desired gap 102, the
combined surface area of the surfaces 151 and 152 accessible to the
fluid, and other such factors. As previously described, the fluid
supply input 50 (see FIG. 1) receives the fluid from the reservoir
(not shown). The fluid passes through the fluid supply channel 52,
through the face seals 47 and 157, through the fluid channel 182,
and into the chamber 180.
[0043] Still referring to FIG. 3, the fluid in the chamber 180 may
have a single possible leak path at the outer periphery between the
mounting plate 142 and the spring engaging plate 162. This leak
path can be sealed using one or more ring seals 163a that are
disposed along the outer periphery of the leak path between the
pressure-actuated member 144 and the spring engaging plate 162 at
interfaces 165. The seals 163a are positioned as such to prevent
fluid leakage through the leak path. An inner seal 163b can be
arranged at the inner periphery between the spring engaging plate
162 and the second spline member 164. As previously described, the
piston 140 remains rotationally stationary relative to the hub 160
in this embodiment, so the seals 163a do not endure a relative
rotational motion. The spring engagement plate 162 can be fixed
relative to the second spline member 164, such that the seal 163b
does not endure relative movement during operation. When the seals
163a and 163b are internal to the clutch device 100 and are limited
to such minimal (or no) sliding motion, the possibility of
contaminants entering the chamber 180 through the seals 163a and
163b may be significantly reduced. Such a reduction in
contamination may increase the longevity the clutch device 100 and
may reduce the need for repair or replacement.
[0044] Referring again to FIGS. 1-3, the piston 140 in this
embodiment serves as both the component that shifts to engage the
input portion 110 (via the input ring 112) and the component that
receives an output instrument (such as the fan blade device 20
depicted in FIG. 1). The output instrument mounted to the studs 23
of the piston 140 may also be shifted in the axial direction as the
piston 140 is actuated, but the displacement in the axial direction
may be relatively small such that this shifting motion has little
or no impact on the output instrument. Similarly, the displacement
in the axial direction may be relatively small such that the
shifting motion of the piston 140 relative to the hub 160 has
little or no impact on the longevity and performance of the seals
163a.
[0045] In some embodiments, the clutch device 100 can be readily
removed from the drive pulley 30 without requiring disassembly of
the input portion 100 from the output portion 130. For example, the
clutch device 100 is mounted to the drive pulley 30 by the mounting
bolts 32. Upon removal of the bolts 32 from the drive pulley 30,
the and subsequent removal of the clutch device 100 from the drive
pulley 30, the internal spring 170 is not permitted to freely
expand and thereby cause disassembly of the clutch device 100
(e.g., the spring 170 is not permitted to unexpectedly expand and
separate the piston 140 and hub 160 when a user attempts to remove
the clutch device 100 from the drive pulley 30). Instead, the
components of the clutch device 100, such as the input portion 110,
the piston 140, the hub 160, and the spring 170, remain in the
assembled state during the process of removal from the drive pulley
30.
[0046] To disassemble components of the clutch device 100 (e.g.,
for purposes of replacing the friction ring 132 or other repairs),
the lock nut 116 can be removed from the second spline member 164.
Once the lock nut 116 is removed, the bearings 114 and the input
ring 112 can be removed. As previously described, the piston 140
includes the mounting plate 142 and the spring-engaging member 146
that are assembled together using the assembly bolts 145. To
disassemble the piston 140 (e.g., separate the pressure actuated
member 146 from the mounting plate 142), the bolts 145 can be
removed. In this way, the clutch device 100 can be disassembled at
another time (e.g., after the clutch device 100 is transported to a
work bench or other area). As described in more detail below, the
clutch device 100 can include the shut-off system that causes the
fan blade device 20 to continuously rotate with the input portion
so as to indicate to a vehicle operator that the friction ring 132
has worn below a threshold thickness. In such embodiments, the need
for routine disassembly of the clutch device merely for visual
inspection of the clutch ring can be reduced or eliminated, thereby
reducing the down-time in which the vehicle is not in use due to
service.
[0047] Referring now to FIGS. 4A-4C, after an extended period of
use of the clutch device 100 (e.g., repeated transitions of the
friction ring 132 between the disengaged and engaged positions),
one or both of the engagement surfaces 114 and 134 can wear causing
the piston 140 to travel farther axially toward the pulley 30
before the surfaces 114 and 134 engage (identified by a wear
displacement 106 in FIG. 4A). In particular embodiments, the
engagement surface 134 of the friction ring 132 will wear down such
that the friction ring thickness is reduced below a threshold
thickness level, which indicates that replacement of the friction
ring 132 is required. In one example, the friction ring 132 can
comprise a material that wears at a rate greater than does the
input ring 112. As such, the friction ring 132 may be replaced
after a period of use when the friction ring thickness wears below
a predetermined level. The clutch device 100 can be configured to
impart continuous friction engagement between the friction ring 132
and the opposing surface 114 of the input portion 110 in response
to the friction ring 132 wearing down below a threshold thickness.
In particular embodiments, the clutch device 100 is operable to
prevent movement of the friction ring 132 from the engaged position
to the disengaged position in response to the friction ring 132
wearing down below the threshold thickness.
[0048] For example, as seen in FIG. 4A-4C, as clutch material is
worn from the friction ring 132, the piston 140 will travel farther
axially in the direction of the pulley, before the engagement
surfaces 114 and 134 frictionally engage and cause the output
portion 130 to rotate with the input portion 110. After a selected
amount of the material has worn away from the friction ring 132
resulting in the predetermined wear displacement 106, the thickness
of the friction ring 132 then reaches a level below a predetermined
threshold thickness. When the friction ring 132 is worn below the
threshold thickness, the clutch shut-off system 150 is
self-activated, without any user intervention or external controls,
to prevent disengagement at the friction surfaces 114 and 134
between the input portion 110 and the output portion 130 of the
clutch device 100.
[0049] Referring to FIGS. 4A and 4C, in some embodiments of the
clutch shut-off system 150 is entirely housed in the output portion
130 and comprises at least two elements. In this embodiment, the
two components of the clutch shut-off system 150 comprise a seal
member 156 and the interior surface 151 of the plate 142, which at
least partially defines a fluid-receiving space to receive the
pressured fluid. The seal member 156 can be arranged at an axial
spacing from the interior surface 151 (refer to FIG. 2A) when the
friction ring 132 has a thickness greater than the threshold
thickness. The seal member 156 engages the interior surface 151
(refer to FIGS. 4A and 4C) to form a fluid seal only when the
friction ring 132 is worn down below the threshold thickness. In
the depicted example, an axial-facing portion of the seal member
156 abuts with the interior surface 151 (which is an axial surface
that opposes the seal member 156) when the friction ring 132 is
worn down below the threshold thickness. When the seal member 156
sealingly engages the interior surface 151, an exposed surface area
of the fluid-receiving chamber 180 that is exposed to pressurized
fluid is substantially reduced (e.g., only the circular area inside
the diameter of the seal member 151 rather than both surfaces 151
and 152). Such a reduction in the exposed surface area of the
fluid-receiving chamber 180 reduces the amount of force provided by
the pressurized fluid, which in this embodiment prevents the fluid
pressure force from overcoming the spring 170. Accordingly, the
clutch shut-off system 150 prevents movement of the friction ring
132 to the disengaged position in response to the friction ring 132
wearing down below the threshold thickness, and does so without
user intervention or external controls.
[0050] Referring now to FIGS. 4C and 5, the seal member 156 of the
clutch shut-off system 150 may be positioned in a groove on a front
face of the second spline member 164. The seal member 156 can be
configured such a portion of the seal member protrudes axially
forward from the groove so as to engage with the interior surface
when the piston 140 is required to travel the displacement distance
106 (after the friction ring 132 is worn below the threshold
thickness). In this embodiment, the second spline member 164 and
the plate 142 of the piston portion 140 rotate together, so the
seal member 156 is not exposed to relative rotational motion when
it engages with the interior surface. When the seal member 156 form
a seal engagement with the interior surface 151, the
fluid-receiving chamber 180 (see FIG. 2A) may not be in fluid
communication with the fluid channel 182 and the fluid reservoir
(not shown). For example, an outer portion 184 of the fluid chamber
180 that is radially more distant from the central axis 35 than the
seal member 156 may be sealed from an inner portion 186 (see FIG.
3). In particular, the area of the plate 142 that is inside the
diameter of the seal member 156 can be exposed to the pressurized
fluid, but the portion of the plate 142 (e.g., along the other
interior surface 152) that is radially outward from the seal member
156 will not be exposed to the pressurized fluid. Thus, the amount
of force provided by the pressurized fluid in the fluid-receiving
space of the clutch device 100 is substantially reduced when the
seal member 156 forms a seal against the interior surface 151,
thereby preventing the force from the pressurized fluid from
overcoming the bias force of the spring 170. In such circumstances,
the friction ring 132 is continuously maintained in the engaged
position both when the pressurized fluid is input into the clutch
device 100 and when the pressurized fluid is withdrawn from the
clutch device 100. In the configuration depicted in FIG. 4A-4C, the
clutch device 100 can continue to operate the fan blade device 20
such that the fan blades 22 will continuously rotate with the input
portion 110, providing a indication to the vehicle operator that
the fan clutch device 100 requires service (e.g., to replace the
friction ring 132).
[0051] As shown in the example in FIG. 5, the clutch device 100 in
this embodiment is restricted from transitioning the friction ring
132 to the disengaged position (FIG. 3) because the clutch shut-off
system 150 self-activated in response to the friction ring wearing
down below a threshold thickness. In this example, the friction
ring 132 has worn below predetermined level, so the interior
surface 151 of the mounting plate 142 contacts with the seal member
156, which in this embodiment comprises an o-ring seal partially
protruding from the front axial face of the second spline member
164. When in abutment with the interior surface 151, the seal
member 156 fluidly isolates the outer portion 184 of the chamber
180 from the fluid channel 182. In this position, when fluid
pressure is applied through the fluid channel 182, the pressurized
fluid acts upon only the inner portion 186 of the chamber 180
(e.g., the circular area of the interior surface 151 that is inside
the diameter of the seal member 156). However, the seal member 156
blocks the pressurized fluid from acting upon the outer portion 184
of the chamber 180 (e.g., the portion that is radially outward of
the seal member 156). As such, the pressurized fluid is only able
to exert pressure on a smaller area of the piston portion 140
(e.g., the circular area inside the diameter of the seal member 156
as shown in FIG. 5) as compared to the larger exposed area of the
piston portion 140 (along both surfaces 151 and 152 as shown in
FIG. 3) when the clutch shut-off system 150 is not activated.
[0052] Because the clutch shut-off system 150 in this embodiment
limits the amount of exposed area for the pressurized fluid, a
smaller axial force is imparted from the pressurized fluid to the
piston portion 140 (refer to FIG. 5) than in the configuration
where the fluid can access the entire chamber 180 (refer to FIG.
3). In this embodiment, the force imparted by the pressurized fluid
on the smaller area 186 is not great enough to overcome the force
bias of the spring 170. As such, even when fluid pressure is
applied to disengage the clutch device 100, the clutch shut-off
system 150 prevents the clutch device 100 from responding such that
the friction ring does not transition away from the engaged
position to the disengaged position.
[0053] In some embodiments, the clutch device 100 can be configured
such that a user can become aware that the friction ring 132 has
worn below the threshold thickness level without the need for a
visual inspection. For example, in the embodiment previously
described in connection with FIG. 5, the clutch device 100 will no
longer transition the friction ring 132 from the engaged to the
disengaged position. Thus, the clutch device 100 remains in the
engaged position, causing the output portion 130 to remain
rotationally coupled to the input portion 110. In this condition,
the cooling fan device 20 will continuously rotate with the input
portion 110, which serves as a notification to the vehicles
operator or another user that the clutch device 100 is ready for
service. Advantageously, however, even when the friction ring 132
of the clutch device 100 is worn down below the threshold level,
the fan device 20 will continue to cause a cooling flow of air
allowing the vehicle's engine and radiator. Thus, the vehicle
operator can continue to operate the vehicle without fear of
overheating and without the need to immediately cease vehicle
operation to apply "come home" bolts or other intervention to the
clutch device 100. When it is convenient for the vehicle operator,
the vehicle can be taken to a service station for inspection of the
clutch device 100, replacement of the friction ring 132, and the
like.
[0054] It should be understood from the description herein that the
drive member may have a configuration other than the drive pulley
30 shown. For example, the drive member may be a shaft or gear that
is urged to rotate by the engine (via a direct or indirect
coupling). In such embodiments, the input ring 112 or other
component of the input portion 110 can have a mounting
configuration to removably attach to that particular drive source
or may have an adapter member connected therebetween.
[0055] In yet another embodiment, the friction ring 132 may be
mounted to the input ring 112 or to another component of the input
portion 110. In these embodiments, the opposing friction surface
may be arranged on a portion of the piston 140 (e.g., the
spring-engaging member 146, the mounting plate 142, and the like)
or otherwise coupled to the output portion 130. As such, the piston
140 can be actuated to cause the friction ring 132 to be
selectively engaged or disengaged with the opposing friction
surface.
[0056] A number of embodiments of the invention have been
described. Nevertheless, it will be understood that various
modifications may be made without departing from the spirit and
scope of the invention. Accordingly, other embodiments are within
the scope of the following claims.
* * * * *